The objectives of the proposed work are: 1) to purify individual, abundant nonhistone chromatin proteins that occur in much higher amounts in a line of hepatoma tissue culture cells (HTC cells) than in adult rat liver and that are in this sense tumor-enriched species; and 2) to begin to elucidate the functions of these proteins. Individual nonhistone protein will be purified without exposure to overt denaturing conditions using immunoadsorbents, DNA-sepharose chromatography, and standard techniques of protein purification. Starting with two HTC cell-enriched nonhistones that have already been purified, we will develop radioimmunoassays for individual proteins. Key physicochemical properties of the proteins will be determined and the interaction of the proteins with DNA studied. We will investigate the relationship of the proteins to the nucleosome model of chromatin structure and, by determining the amounts of the proteins in various types of liver and in HTC cells grown under a variety of conditions, attempt to determine the biological significance of the proteins' enrichment in HTC cells.